A packaged focal plane array comprises a detector array, an associated read-out circuit, and a transmissive cover that seals the detector array and read-out circuit. One way in which focal plane arrays are packaged involves first fabricating several detector arrays with their corresponding read-out circuits. Each focal plane array is then individually covered and sealed with a transmissive cover. The cover is typically applied in a separate process and is made of germanium or float-zone silicon.